Insulation construction for cryogenic containers



March 22, 1966 c. R. NAVIKAS INSULATION CONSTRUCTION FOR CRYOGENICCONTAINERS 2 Sheets-Sheet 1 Original Filed April 13, 1959 V mR S E L R AH C A T TORNE Y March 22, 1966 c. R. NAVIKAS 3,241,702

INSULATION CONSTRUCTION FOR CRYOGENIC CONTAINERS Original Filed April13, 1959 2 Sheets-Sheet 2 INVENTOR. CHARLES R. NAVIKAS Za M UnitedStates Patent 3,241,702 INSULATION CONSTRUCTION FOR CRYOGENIC CONTAINERSCharles R. Navikas, Indianapolis, Ind., assignor to Union CarbideCorporation, a corporation of New York Original application Apr. 13,1959, Ser. No. 805,793, now

Patent No. 3,019,573, dated Feb. 6, 1962. Divided and this applicationNov. 2, 1961, Ser. No. 149,709

1 Claim. (Cl. 220--9) This invention relates to an insulationconstruction in combination with a cryogenic container, said assemblybeing made by a method and apparatus for applying a composite insulatingmaterial about a container, particularly the multi-layer insulatingmaterial employed in the solid-invacuum type insulation described in thecopending application of L. C. M-atsch, Serial No. 597,947, filed July16, 1956, now US. Patent No. 3,007,596.

The aforesaid patent application discloses a multi-layer insulatingmaterial comprising generally alternating layers of a thin, flexiblemetal foil, such as aluminum, and a porous fibrous sheeting of lowconductive material, such as glass fiber, which are conformably wrapedaround a cylinder under suitable tension.

It is possible to hand Wrap the sheetings of foil and fiibrous materialaround a container and end up with an insulation wrapping which willperform satisfactorily in the vacuum insulating space of a double walledcontainer. However, such a procedure is not only time consuming andcumbersome, and in some instances not susceptible of practice because ofthe relative magnitudes of the container sizes and weights involved, butis relatively expensive.

The tension applied to the Wrapped composite insulation is an essentialvariable which may tend to downgrade the insulating system. For example,as explained in the aforesaid patent application, tightening of theinsulation wrapping causes the fibrous sheeting to be compressed andincreases the effective path of solid conduction therethrough. On theother hand, wrap-ping the insulation too loosely decreases the number offoil turns and increases heat leak by radiation therethrough. Optimumresults obtain somewhere between these extremes.

Furthermore, aluminum foil must be handled with great care as it maytear because of uneven or undue tension or other reasons. Applying thesame tension to the foil and to the fiber sheeting is furthermoreundesirable, because the fiber sheeting is considerably weaker intension than the foil. It is also a problem to apply a suitable numberof turns of composite insulation to provide an insulation wrapping of aprescribed thickness. In addition, there is a problem in handling ordisposing of the paper backing, such as found in glass fiber rolls,during the process of wrapping the fiber sheet and aluminum foil arounda container.

For these and other reasons, it is desirable to provide a reliable meansfor achieving a satisfactory wrapping of composite insulation about acontainer without encountering the aforementioned difficulties.

It is, therefore, an important object of the present invention toprovide an improved method and apparatus for wrapping a container withcomposite layers of insulating material that results in a suitable andsubstantially uniform tension throughout the insulation wrapping.

It is another object of the invention to provide a convenient andeconomical method and apparatus for applying a wrapping of compositelayers of insulation onto a container in a manner that is effective andnot damaging to the composite layers of insulation.

Other objects, features and advantages of the invention will be apparentfrom the following detailed description of a preferred embodimentthereof, taken in conjunction with the attached drawings in which:

FIG. 1 is a schematic diagram showing an insulation wrapping machineembodying the principles of the invention;

FIG. 2 is an isometric view of a preferred modification of a wrappingmachine showing the driving mechanism therefor;

FIG. 3 is an enlarged fragment of the view shown in FIG. 2 andillustrating the operation of the foil piercing roll; and

FIG. 4 is an isometric view of an article being Wrapped according to.the invention.

The preferred practice of the invention will be described in terms ofwrapping a container with a composite insulation of aluminum foil andglass fiber sheeting. It is to be understood, however, that suchdescription is presented as illustrative only and that it is notintended to limit the scope of the invention.

Shown in FIG. 1 is a preferred diagrammatic illustration of aninsulation wrapping machine embodying the principles of the presentinvention comprising a pair of frame members 10, only one being shown,upon which are mounted a metal foil carrier roll 12 from which aluminumfoil 14 is supplied, a fiber insulation stock roll 16 from which glassfiber sheeting 18 is fed, and a wind-up drum or container 20, which isthe vessel to be insulated, about which a composite of the aluminum foil14 and the glass fiber sheeting 18 is wound. The roll of aluminum foil14 is mounted on the carrier roll 12 so that it will unroll and passaround the container 20, where it is superimposed upon glass fiber sheet18 and Wrapped therewith around the container.

The glass fiber sheet material 18 is commercially available and usuallysold in rolled sheet form with a paper backing 26. Since the paperbacking is not used in the formation of the insulation product, it isseparated and collected on paper roll 28 as the fiber insulation roll 16is unwound. Glass fiber sheet 18 is advanced from roll 16 and is fedonto the container 20 where it meets foil 14 and is plied between thelayers of foil wrapping.

In the preferred modification of the invention shown in FIG. 2, meansare provided for piercing the metal foil in order to form passagesthrough the otherwise vapor-impervious barrier. This aids in completeevacuation of the insulation when it is installed in a container shellin the manner illustrated in the aforesaid application. To this end, aperforating roll 22 is rotatably mounted in the frame members 10 betweenthe foil carrying roll 12 and the container 20. The aluminum foil 14 onroll 12 passes around the perforating roll 22 and is then conveyed tothe container 20. The surface of the perforating roller 22 is providedwith a plurality of generally radially extending projections 24preferably arranged in helical rows of spirals. This arrangement permitspiercing at any given instant a minimum number of uniformly spaced holesacross the width of the metal foil 14 Without significantly affectingthe tensile strength of the foil. In addition, the helical arrangementaffords means for providing a suitable number of perforations in thefoil 14 without noticeably reducing the shielding properties thereof.

The enlarged view of the piercing roll shown in FIG. 3 illustrates thepreferred configuration for the projections 24. Projections 24 should bebevelled with the leading bevel edge first contacting the foil. Thispierces a hole 25 in the foil 14, and folds over the struck out portionor flap 27, thereby preventing it from flapping back and closing thehole.

Means are provided for driving the container 20 and the feed rolls 12,16 and paper roll 28. For this purpose, the container 20 is rotatablymounted between headstock and tailstock supports 30, 30 extending fromthe frame members 10. Supports 30, 30 may for example be suitably springloaded by means not illustrated but wellknown to those skilled in theart, for ease in positioning the container therebetween. Headstock 30 isrotatably driven by a chain belt 32 from a pulley 34. Pulley 34 ismounted on a shaft 36 journalled in a bracket (not shown) on the machineframe. It is driven from a speed reducing gear box 38 connected to amotor 40.

The metal foil carrier roll 12 is connected to the paper collecting roll28 through a pulley drive comprising a driver pulley 42 mounted on theaxis 13 of roll 12, an intermediate speed regulating mechanism 44suitably rotatably mounted in the frame 10, and a pulley belt 46 oversaid pulleys 42 and speed regulating mechanism 44. By means of a belt48, the speed regulating mechanism 44 drives a driven pulley 50 mountedon the axis 29 of paper roll 28. As container 20 rotates, it pulls metalfoil 14 from roll 12 and causes rotation of roll 12. Rotation of roll12, in turn, causes paper roll 28 to rotate and pull paper backing 26from the fibrous material 18. This causes glass fiber roll 16 to rotateand feed fibrous sheeting 18 toward container 20.

The speed regulating mechanism 44 between driver pulley 42 and drivenpulley 50 provides the means for adjustably controlling the relativesurface speeds of paper roll 28 and foil roll 12, such means beingwell-known by those skilled in the art. Preferably, the surface speed ofpaper sheeting 26 is adjusted to be slightly greater than the surfacespeed of foil 14. This removes substantially all the tension from thefibrous material 18 which is inherently a weak material and could easilyseparate under tension. Consequently, the fibrous sheeting 18 isliterally laid on the container 20 without substantial tension. Thecomposite of aluminum foil and fibrous layer insulation is wound up intoa roll under moderate tension about the container 20. Tension of themetal foil is controlled by means of a Prony brake or other adjustablefriction brake 54 located on the axis 13 of the roll 12.

The method and apparatus of the invention can be performed and operatedby either one or two men, or can be fully automated if so desired. Afavorable test of the invention was conducted under the followingconditions:

A roll of .0004" thickness aluminum foil and 54" in width, mounted onroll 12, was manually unrolled to provide a sufiicient length ofaluminum foil sheeting 14 to pass around the perforating roll 22 andextend up to the container 20. The end of the aluminum foil 14 was tapedto the cylindrical surface of the container 20, the outside diameter ofwhich was approximately 15 /2". Rotation of the container 20 wasgradually started by a first operator by means of a suitable control onmotor 40. After approximately one-half turn of foil had been wrappedaround the container, a second operator fed the free end of the fibersheet 18, 57" in width and A" thick, from fiber roll 16 into the nipbetween the overlying foil 14 and container 20 as shown in FIG. 2. Thebacking paper 26 was taped to the backing paper roll 28.

The second operator firmly grasped roll 16 to halt its rotation, andrelaxed his hold when necessary to control the feed of the fibersheeting 18 during the starting period as it was introduced between thelayers of aluminum foil. This control is possible due to the fact thatthe fiber roll 16 is mounted between two cone type rolls. Once the fibersheeting had been gripped by foil wrapping, the second operatormanipulated the friction brake 54 to achieve the proper tension or foil14 and adjusted the speed of the fiber sheet 18 by means of the speedregulating mechanism 44.

It will be appreciated that care must be exercised in the feeding of thefiber sheeting 18 that no tension is applied thereto. For this purpose,and in order that the operator may have some leeway in adjusting thespeed regulating mechanism 44 or the friction brake 54, a liberal amountof slack or sag must be provided in the fiber sheeting 18 as illustratedin the drawings. This slack is an excellent indication to the operatorthat the fiber sheeting is not under tension and amply warns him when anadjustment is necessary.

After the initial feeding of fiber and foil, the first operatorcontrolled the speed of rotation of the container 20 and observed thefoil 14 for rips or tears, and the second operator carefully watched theslack in the fiber sheeting 18 and properly adjusted the speedregulating mechanism 44 to compensate for changes in the sag of thefiber sheeting. During this period, there was no tension on the fibersheeting 18, tension being solely on the foil 14 and the backing paper26. The number of turns of composite insulation was suitably recorded,for example, by a rod 58 extending radially from the supporting shaft ofheadstock 30 and terminating in an offset arm 60 which slides over arecording tab or detent (not shown) fixed to the frame 10.

After 25 layers of composite insulation had been applied to the wrappingmachine, the machine was stopped, and the circumference of theinsulation was measured. The outside diameter of the insulation was thencalculated to be 19". This dimension afforded sufficient clearance forthe insulation wrapped container to be inserted into an outer containerwhose inside diameter was approximately 19%".

One extra turn of aluminum foil was applied to the container by firmlyholding roll 16 and rotating container 20, thereby placing fibersheeting 18 under tension and causing it to tear in a transversedirection. T o prevent the loosening and unrolling of the insulationwrapping, the end of the aluminum foil was framed in place. Followingthis, the marginal portions of the composite insulation were folded inat both ends of the container 20 and taped in place. In so doing, asmall portion of the insulation 21 was first pressed down and foldedinwardly relative to the substantially cylindrical medial portionthereof which surrounds the container 20. The remaining unfoldedmarginal end portions 23 were then similarly folded inwardly in smallportions until at least one of the end portions was convex in shape.This was carefully done to preserve the alternate layers of foil andfibrous sheeting and to avoid the possibility of the foil contacting thecontainer. In this respect, the wider fibrous sheeting (57" in width)also preserved the spacing of the foil (54" in width). The wrappedcontainer 20 was then removed from the wrapping machine and placed in aproduction line for assembly inside an outer container (not shown) tosubsequently provide the insulation substantially shown and described inthe aforesaid copending application.

It will be understood that although the insulation wrapping machine andinsulation wrapping method of the invention have been described withreference t wrapping a cylindrically shaped container, the invention isnot intended to be so limited. Modifications and variations may beeffected without departing from the spirit and scope of the invention.

This is a divisional application of copending application Serial No.805,793, filed Apr. 13, 1959 in the name of C. R. Navikas, now U.S.Patent No. 3,019,573.

What is claimed is:

An insulation construction in combination with a cylindrical vacuuminsulated cryogenic container comprising a cylindrical vessel havingmultiple layers of composite insulating material Wrapped around themedial portion thereof, said composite insulating material consisting ofalternating layers of thin flexible metal foil and porous fibroussheeting of low conductive material, said multiple layers of compositeinsulating material extending beyond at least one end of said vessel,the length of said layers of fibrous material extending further beyondsaid end than the layers of said metal foil, the portions of saidcomposite insulating material extending beyond said end being foldedinwardly relative to said medial portion in overlapping increments,whereby metal foil to foil contact between adjacent foil layers isavoided.

References Cited by the Examiner UNITED STATES PATENTS 1,317,957 10/1919Carroll 161145 X 2,726,977 12/1955 See et a1. 154-44 2,830,000 4/1958Labino 161196 2,863,179 12/1958 Gaugler 220-9 X 2,970,736 2/1961 Baughan22 93.5 3,006,403 10/1961 Cooper et al. 15444 3,007,596 11/1961 Matsch154-44 JACOB H. STEINBERG, Primary Examiner.

HAROLD ANSHER, EARL M. BERGERT, Examiners.

